Non-alcoholic fermented beverages such as wines have become of great interest because they offer traditional wine flavor without the unhealthful and sociably objectionable side effects of the alcohol However, until the present invention there has been no process for producing non-alcoholic fermented beverages of flavor, aroma and color solids equivalent to traditional alcohol-containing beverages.
Non-alcoholic wines have been marketed for a number of years, but the techniques applied in the production of these wines have produced off-flavors in the efforts to remove all of the alcohol. For example, the alcohol can be distilled off, but in the process the wine is cooked or at least de-natured and most of the wine flavor and aromatics are driven off or altered. Another method is to reduce alcohol content is by dilution with water. This results in a "thin" taste which one can expect from a watered-down wine or other fermented beverage.
Reverse osmosis, as it has been recently applied, has proved satisfactory only in connection with producing lowered alcoholic content beverages (down to about 5-6%), but not completely non-alcoholic beverages. This is in large part due to the low alcohol barrier problem encountered in reverse osmosis processes. When the alcohol content of a beverage being processed by reverse osmosis drops to about 5% by volume alcohol, the reverse osmosis membrane rejects the alcohol, i.e. it will not pass through freely. This "barrier" phenomenon makes removal of alcohol to below 5% by volume by conventional reverse osmosis almost impossible.
Wuchterpfennig & Neubert in Brauwelt No. 47 (1976), as reported in Chemical Abstracts 86 (3):15164 f (1987), disclosed partial dealcoholization of beer by reverse osmosis using a celluose acetate membrane having a salt rejection value of 90-96% at high pressure in a plate-type unit. The alcohol was reduced from 40.1 g/L to 17.0 g/L.
Bonneau in U.S. Pat. No. 4,499,117 (1985) used an ultrafiltration membrane having a separation threshold of 10,000 daltons under low pressure, followed by a single reverse osmosis step applied to the ultrafiltrate permeate using a Degremont brand osmoser of aromatic polyamid hollow fibers having a molecular weight pass level of about 250, followed by evaporation and distillation under vacuum (0.015 atomospheres) at low temperature (45 degrees C.). The wine is reduced from 12-13 degrees Gay Lussac to about 5 degrees GL. Lyophillization may also be employed to produce a dessicated concentrate to form a dry beverage mix.
Goldstein et al. in U.S. Pat. No. 4,612,916 (1986) applied reverse osmosis to wine and malt beverages using a Patterson Candy International (Great Britain) brand RO unit employing a ZF 99 membrane and succeeded in reducing beer from 3.7% by weight to 1.25-1.85% by weight. The ZF-99 membrane used was a polyamid polysulfone-supported TFC rated for pressures up to 900 psi. Goldstein also compared the TFC membrane to a cellulose acetate membrane.
Beaumont in U.S. Pat. No. 4,401,678 (1983) used ultrafiltration on both grape juice and wine fermented therefrom. In processing grape juice, the ultrafiltration unit employed a molecular weight cutoff of 175-200 for the purpose of removing methyl anthranilate and other objectional "foxy" flavors present in Labrusca-type wine grapes. Water was added to the grape juice retentate at a flow rate of approximately the same as the flow rate of filtrate, but only until 25-75% of the initial volume of juice passes through the membrane. The retentate retains the same volume and the same amount of sugar for subsequent fermentation. The wine resulting from the fermentation had decreased flavor and lowered Labrusca Flavor Index. Beaumont also ultrafiltrated fermented wine using the same permeable membrane to concentrate the wine to a volume of 25-75% of the initial volume with the same alcohol content as the feedstock wine, the concentrate thus having a intensified color and lowered LFI. No water was added to the wine concentrate. The ultrafiltration was run at approximately 500-1000 psi at 15-20 degrees C., and reportedly decreased LFI by at least about 50%. The membrane type was not disclosed. The term reverse osmosis in this patent apparently was intended to include both ultrafiltration and diafiltration.
Madsen, in Australian patent application 66334/74 published Sept. 25, 1975, teaches that heat concentration causes irreversable changes to grape juice which are detrimental to the quality of wine produced from the concentrated juice Madsen concentrates grape juice by reverse osmosis using cellulose acetate membranes. The resulting grape juice was concentrated down to 60% of original volume, and had higher sugars and lower acid content.
Keufner, in U.K. patent application GB 2,133,418A published July 25, 1984, describes a process of concentrating beer and wine by passing it through a reverse osmosis semipermeable membrane, and later adding liquid to form a reconstituted beverage. The reconstituting water can be reverse osmosis treated water from which up to 99% of the minerals have been removed. The membrane was a TFC consisting of a cross-linked polymeric amine composited on a polymeric support. The reverse osmosis system was operated at a temperature in the range of about -2% to about 40 degrees C. and at pressure of from about 100-1100 psig in a non-oxidizing atmosphere provided by the presence of carbon dioxide. The reconstituting water is added after completion of the reverse osmosis process. Approximately 45% of the alcohol and 75% of the water was removed from the beer in the process The resulting beer contained 2.3% alcohol by weight. Of three samples produced, one had a slight burnt note in the aroma, and another sample was quite thin indicating not enough bodying ingredients remained after dilution. These can be characterized as light beers with low alcohol content.
Guinness Company's Belgian patent 717,847 (Dec. 1968) employed reverse osmosis under a non-oxidating atmosphere to produce a concentrate for export which is reconstituted with locally produced alcohol. The preferred membrane was cellulose acetate as taught by U.S. Pat. No. 3,133,132. Also mentioned as membrane materials were polyvinyl acetate and polyacrylates. This patent teaches post-shipment reconstituting to the same volume with alcohol and water, or with water alone to get a non-alcoholic or almost entirely non-alcoholic beverage.
Accordingly, there is a need in the art to provide a process for production of low and non-alcoholic wines which retain all of the traditional wine aromas and flavors at full strength without dilution of the wine, and also remove the objectionable alcohol content.